Bilby

One of Australia's best-known marsupials, the greater bilby, has been immortalised as our very own bearer of Easter goodies. But bilbies are revered for a variety of other ecological and cultural reasons, too.

The bilby is an important ecosystem engineer. It’s an excellent digger and so many other species reap the rewards of its hard work. When bilbies aren't living in their complex burrows, which can be up to three metres long and two metres deep, other animals like insects, reptiles, birds and small mammals take up residence. The burrows provide vital shelter from predators and high summer temperatures.

Bilbies might be small but they punch well above their weight. They can shift more than 1.5 tonnes of soil per kilogram of body mass in a single year as they construct and maintain their subterranean homes.

But every year bilby populations continue to decline and there’s growing concern that it may eventually become extinct. While much is known of bilby populations in south west Queensland, very little is known from the Kimberley but our work with Ranger groups indicates that the Kimberley may support the last large populations of this species.

What we're doing

Kimberley Bilby Project

The Kimberley Bilby Project is a ground-breaking project that combines the traditional knowledge of the southern Kimberley Indigenous rangers and communities (Yawuru, Nyul Nyul, Bardi Jawi, Karrajarri, Nyikina Mangala, Nugurrura, Gooniyandi and Paruku Rangers) with WWF, Department of Parks and Wildlife, Kimberley Land Council and Environs Kimberley expertise. Traditional Owners are telling their stories about the bilby (nyarlku) and helping to coordinate its protection across the southern Kimberley.

Bilby Surveys

With the support of Lotterywest, WWF is harnessing the experience of Indigenous ranger groups to conduct science-based assessments of the status and condition of threatened species across the southern Kimberley, including the bilby. WWF is working with ecologists and eight Kimberley ranger groups to conduct bilby surveys. About 35 Indigenous rangers are now trained to work on country and bilby populations have been found at a number of locations. Thanks to Department of Parks and Wildlife researchers, all groups are now using standardised methods.

Learning about bilby behavior

The next phase of our project will include undertaking research with the rangers and other researchers to better understand how bilbies are using their local environments, including what impacts fire and grazing have. This will involve genetic analysis of bilby scats (poo) to understand bilby movements at a local and regional scale, habitat use and their dietary preferences. This information will help us to map bilby habitat – information that will feed into fire and feral animal management to protect bilby populations and habitat.

Why it matters

Bilby populations are crashing across Australia, and the Kimberley could be the last place where they occur in relatively healthy numbers. In southwest Queensland, feral cat numbers increase significantly in response to favourable environmental conditions and levels of predation on bilbies also increase as other prey sources (e.g. long-haired rats) are exhausted. In the central deserts and Pilbara, cats and also foxes have taken a deadly toll. Bilbies are barely hanging on in small, isolated populations, and there’s mounting concern that we may lose them from the wild forever.

We know almost nothing about the fragmented Kimberley bilby populations. They live in very different habitat to that of the deserts, where almost all previous research has been conducted. We don’t know what resources bilbies need and how they use their environment throughout the year, whether they’re under threat by cats and inappropriate fire regimes, or even if foxes are a problem. Research in the Kimberley is urgently needed.

And there may be much more at stake than the survival of bilbies themselves. As well as providing accommodation for others, bilbies constantly turnover soil, improving soil health by mixing through organic matter and bringing deep soils and their nutrients to the surface. Their diggings also provide sites for water to penetrate and for the spread of important mycorrhizal fungi (which help plants to absorb nutrients and cope with Australia's nutrient-poor soils) across the landscape. As you can see, the bilby delivers much more than just Easter eggs.

Macrotis lagotis

Species Bio

Common Name

Bilby

Scientific Name

Macrotis lagotis

Stats

This species grows to 55 cm long with a tail up to 29 cm long

Status

Listed as Vulnerable under EPBC Act and IUCN Red List.

Before European settlement the Greater Bilby was found on over 70% of the Australian mainland; the species now only occurs in less than 20% of its former range.

Did you know?

One Bilby may make up to twelve burrows within its home range to use for shelter.

Threats

Introduced predators, inappropriate fire regimes, and the impacts of grazing and landclearing are key threats to the continued survival of bilbies in the Kimberley. Wild cattle and sheep compete with bilbies for food, and foxes and feral cats also prey on them. These threats interact with each other in complex ways and impact differently in different regions.

A significant amount of money is being spent on captive and fenced bilby populations. WWF would like to see a similar amount spent on better understanding and protecting wild populations.